Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7f4a633d authored by NeilBrown's avatar NeilBrown Committed by Sebastian Reichel
Browse files

twl4030_charger: add software controlled linear charging mode. 



Add a 'continuous' option for usb charging which enables
the "linear" charging mode of the twl4030.

Linear charging does a good job with not-so-reliable power sources.
Auto mode does not work well as it switches off when voltage drops
momentarily.  Care must be taken not to over-charge.

It was used with a bike hub dynamo since a year or so. In that case
there are automatically charging stops when the cyclist needs a break.

Original-by: default avatarAndreas Kemnade <andreas@kemnade.info>
Signed-off-by: default avatarNeilBrown <neil@brown.name>
Signed-off-by: default avatarSebastian Reichel <sre@kernel.org>
parent 22d4c33f

Documentation/ABI/testing/sysfs-class-power-twl4030

+9 −0
Original line number Diff line number Diff line
@@ -24,3 +24,12 @@ Description: 
		"auto" - draw power as appropriate for detected

			 power source and battery status.

		"off"  - do not draw any power.

		"continuous"

		       - activate mode described as "linear" in

		         TWL data sheets.  This uses whatever

			 current is available and doesn't switch off

			 when voltage drops.



			 This is useful for unstable power sources

			 such as bicycle dynamo, but care should

			 be taken that battery is not over-charged.

drivers/power/twl4030_charger.c

+50 −5
Original line number Diff line number Diff line
@@ -24,6 +24,8 @@ 
#include <linux/usb/otg.h>

#include <linux/i2c/twl4030-madc.h>



#define TWL4030_BCIMDEN		0x00

#define TWL4030_BCIMDKEY	0x01

#define TWL4030_BCIMSTATEC	0x02

#define TWL4030_BCIICHG		0x08

#define TWL4030_BCIVAC		0x0a
@@ -35,13 +37,16 @@ 
#define TWL4030_BCIIREF1	0x27

#define TWL4030_BCIIREF2	0x28

#define TWL4030_BCIMFKEY	0x11

#define TWL4030_BCIMFEN3	0x14

#define TWL4030_BCIMFTH8	0x1d

#define TWL4030_BCIMFTH9	0x1e

#define TWL4030_BCIWDKEY	0x21



#define TWL4030_BCIMFSTS1	0x01



#define TWL4030_BCIAUTOWEN	BIT(5)

#define TWL4030_CONFIG_DONE	BIT(4)

#define TWL4030_CVENAC		BIT(2)

#define TWL4030_BCIAUTOUSB	BIT(1)

#define TWL4030_BCIAUTOAC	BIT(0)

#define TWL4030_CGAIN		BIT(5)
@@ -112,12 +117,13 @@ struct twl4030_bci { 
	int			usb_mode; /* charging mode requested */

#define	CHARGE_OFF	0

#define	CHARGE_AUTO	1

#define	CHARGE_LINEAR	2



	unsigned long		event;

};



/* strings for 'usb_mode' values */

static char *modes[] = { "off", "auto" };

static char *modes[] = { "off", "auto", "continuous" };



/*

 * clear and set bits on an given register on a given module
@@ -404,16 +410,42 @@ static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable) 
			bci->usb_enabled = 1;

		}



		if (bci->usb_mode == CHARGE_AUTO)

			/* forcing the field BCIAUTOUSB (BOOT_BCI[1]) to 1 */

			ret = twl4030_clear_set_boot_bci(0, TWL4030_BCIAUTOUSB);

		if (ret < 0)

			return ret;



		/* forcing USBFASTMCHG(BCIMFSTS4[2]) to 1 */

		ret = twl4030_clear_set(TWL_MODULE_MAIN_CHARGE, 0,

			TWL4030_USBFASTMCHG, TWL4030_BCIMFSTS4);

		if (bci->usb_mode == CHARGE_LINEAR) {

			twl4030_clear_set_boot_bci(TWL4030_BCIAUTOAC|TWL4030_CVENAC, 0);

			/* Watch dog key: WOVF acknowledge */

			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x33,

					       TWL4030_BCIWDKEY);

			/* 0x24 + EKEY6: off mode */

			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x2a,

					       TWL4030_BCIMDKEY);

			/* EKEY2: Linear charge: USB path */

			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x26,

					       TWL4030_BCIMDKEY);

			/* WDKEY5: stop watchdog count */

			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0xf3,

					       TWL4030_BCIWDKEY);

			/* enable MFEN3 access */

			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x9c,

					       TWL4030_BCIMFKEY);

			 /* ICHGEOCEN - end-of-charge monitor (current < 80mA)

			  *                      (charging continues)

			  * ICHGLOWEN - current level monitor (charge continues)

			  * don't monitor over-current or heat save

			  */

			ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0xf0,

					       TWL4030_BCIMFEN3);

		}

	} else {

		ret = twl4030_clear_set_boot_bci(TWL4030_BCIAUTOUSB, 0);

		ret |= twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x2a,

					TWL4030_BCIMDKEY);

		if (bci->usb_enabled) {

			pm_runtime_mark_last_busy(bci->transceiver->dev);

			pm_runtime_put_autosuspend(bci->transceiver->dev);
@@ -652,6 +684,8 @@ twl4030_bci_mode_store(struct device *dev, struct device_attribute *attr, 
		mode = 0;

	else if (sysfs_streq(buf, modes[1]))

		mode = 1;

	else if (sysfs_streq(buf, modes[2]))

		mode = 2;

	else

		return -EINVAL;

	twl4030_charger_enable_usb(bci, false);
@@ -750,6 +784,17 @@ static int twl4030_bci_get_property(struct power_supply *psy, 
		is_charging = state & TWL4030_MSTATEC_USB;

	else

		is_charging = state & TWL4030_MSTATEC_AC;

	if (!is_charging) {

		u8 s;

		twl4030_bci_read(TWL4030_BCIMDEN, &s);

		if (psy->desc->type == POWER_SUPPLY_TYPE_USB)

			is_charging = s & 1;

		else

			is_charging = s & 2;

		if (is_charging)

			/* A little white lie */

			state = TWL4030_MSTATEC_QUICK1;

	}



	switch (psp) {

	case POWER_SUPPLY_PROP_STATUS: